Basic principle and measuring method of oscilloscope
Oscilloscope is one kind of electrical measurement equipment with wide application. It could transfer invisible electrical signal to visible image to facilitate people research change processes of all kinds of electricity phenomenon. Oscilloscope use narrow electron beam which consists high-speed electronics and project onto screen coated with fluorescent substance to produce small spot (this is original working principle of analog oscilloscopes. Under the function of measured signal, electronics like the point of a pen which could on screen describe change curve of measured signal during instantaneous value. An oscilloscope can be used to observe the waveform curves of various signal amplitudes varying with time. It could also be used to measure various electricity, such as voltage, current, frequency, phase, amplitude modulation and etc.
(1) pre-adjusting: counterclockwise rotate the brightness button to the bottom, shift vertical and horizontal positions to the middle, set the attenuation gear at the highest level, place scan “outside X gear”
(2) turn on the power, do following steps waiting for one or two minutes after the indicator light is on
(3) adjust luminance first, then adjust the focus, adjust vertical and horizontal displacement to make the light point in center of suitable area.
(4) adjust scan, scan fine tuning and X gain, observe scan.
(5) adjust outside X gear to suitable scan range, observe the voltage waveform according to sine and cosines law on vertical direction inside the device.
(6) Connect the applied voltage to be studied to oscilloscope through Y input and earth. Adjust all gears to suitable position and observe waveform (the picture changes with time) (the synchronous polarity switch can make the starting point of the image start from positive half cycle or negative half cycle.)
(7) If you want to observe the vertical migration of light spot (with one added DC voltage), could adjust scan to “outside X gear”.
In general, the frequency of the calibration signal is 1kHz and the amplitude is 0.5v, which is used to calibrate the internal scanning oscillator frequency of the oscilloscope. If it is abnormal, the corresponding potentiometer of the oscilloscope (internal) should be adjusted until it is consistent.
What does an oscilloscope do?
Oscilloscope is a kind of instrument which is widely used to display the trace change of instantaneous value measured.It can transform the electric signal invisible to the naked eye into visible image, which is convenient for people to study the change process of various electric phenomena. An oscilloscope USES a narrow beam of high-speed electrons to produce tiny points of light by hitting a surface coated with fluorescent material. Under the action of the measured signal, the electron beam ACTS like the tip of a pen and can plot the instantaneous value of the measured signal on the screen.Use oscilloscope to be able to observe all sorts of different signal amplitude the waveform curve that changes with time, still can use it to test all sorts of different electric quantity, if voltage, current, frequency, phase difference, adjust amplitude to wait a moment.
Principle of handheld oscilloscope
A hand-held oscilloscope USES a narrow beam of high-speed electrons to produce tiny points of light on a screen coated with fluorescent material. Under the action of the measured signal, the electron beam ACTS like the tip of a pen and can draw the curve of the instantaneous value of the measured signal on the screen.The use of oscilloscope can observe various different signal amplitude changes with time waveform curve, but also can use it to test a variety of different electricity, such as voltage, current, frequency, phase difference, adjustment amplitude and so on.
How to choose handheld oscilloscope?
Select handheld oscilloscope mainly pay attention to several indicators, bandwidth, storage depth, sampling rate, waveform update rate, isolation channel, display, language, easy operation, and some other kinetic energy (waveform recording, 232/422/485/CAN/I2C/SPI bus decoding) bandwidth: bandwidth is 100M, 200M commonly now, since buy at least buy 100M, each manufacturer is about the same; Storage depth: this various manufacturers vary from 10K to dozens of M have, in general, a few hundred K is enough, too small waveform expansion can not see, square wave are changed into triangular wave. Sampling rate: as long as this index reaches more than 5 times of the bandwidth, all manufacturers have basically reached; Waveform update rate: this index is also a very important index, waveform update rate is too low will lead to some abnormal signals can not be seen; Isolation channel: in the handheld oscilloscope, this is very important, can reduce the risk of accidental short circuit, electric shock, etc., can also reduce the parasitic capacitance during testing, etc., but fortunately, most manufacturers are isolated.